Urinary levels of urokinase-type plasminogen activator receptor are associated with the clinical outcome of pT1 bladder cancers.

G Milanese MD^a, G Muzzonigro MD^a, C Vivani PhD^a,b, F Fazioli PhD^b, CFM Sier MD^c, N Sidenius MD^c, F Blasi MD^c

^aDepartment of Urology, Polytechnic University of the Marche Region, Ancona, Italy, ^bInstitute of Clinical Medicine, Polytechnic University of the Marche Region, Ancona, Italy, ^cDepartment of Molecular Pathology and Medicine San Raffaele Scientific Institute and Hospital, Milan, Italy

AIM The urokinase-type plasminogen activator receptor (uPAR) plays multiple roles in extracellular proteolysis and cell migration. Numerous studies indicate that uPAR is involved in cancer. A soluble form of uPAR (suPAR) is present in blood and urine of healthy people and suPAR levels are increased in the tumor and circulation of cancer patients. We investigated the expression of uPAR in body fluids of patients with renal, bladder and prostate carcinoma in comparison with healthy volunteers. Then the resultant suPAR levels were correlated with the clinical outcome of patients. METHODS Preoperative urine and serum from 92 consecutive patients affected by pT1 renal (n=30), pT1 bladder (n=32) and organ-confined prostate cancer (n=30) were sampled. Urine and serum samples from 30 age-matched healthy volonteers were used as controls. Total uPAR antigen in urine and serum was measured by specific ELISA. Urinary suPAR levels were normalized for dilution by the creatinine content of the samples. Tumor grading was performed according to the WHO system and stage according to the 2002-TNM stage classification system. The Mann-Whitney U test was used to compare differences between groups. Survival analyses were assessed using the Kaplan-Meier method and the log-rank statistic. Multivariate analysis was performed with Cox proportional hazard analyses. RESULTS The median serum levels of suPAR was 3,65 ng/ml ( 1,22) in renal, 3,91 ng/ml ( 1,24) in bladder, 4.11 ng/ml ( 1,53) in prostate cancer and 4,09 ng/ml ( 2,46) in control group. No significant differences were found between the four groups for serum suPAR levels (p=0.433). The median level of urinary suPAR was significantly elevated only in bladder carcinoma patients (8,93 ng/ml;  6,07) as compared to other groups (renal cancer p=0.0008, prostate cancer p=0.004, controls p= 0,0001). To address the hypothesis that elevated levels of urinary suPAR could be associated with a poor prognosis in pT1 bladder cancer patients we performed Kaplan-Meier survival analysis. Follow-up ranged from 24 to 59 months (median 46 months). Stratified by the median urinary suPAR level, patients with high levels had highly significantly poorer recurrence-free (p=0,0028), progression-free (p=0,0020) and cancer-specific survival (p= 0,0068). Fitting the urinary suPAR levels with the serum suPAR levels, age, grade and radical surgery in a multivariate Cox model, the strong prognostic strength of the urinary suPAR level was maintained for recurrence (p=0.025) and progression (p=0,040), but not for bladder cancer death (p=0,096). CONCLUSIONS The enhanced presence of suPAR only in urine of bladder cancer patients could indirectly support the hypothesis that suPAR originates from uPAR expressed and cleaved in the tumor tissue. SuPAR in urine of bladder cancer patients might provide clinically relevant information about the actual state of the tumor and should therefore be studied in larger groups of patients.

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in oral session 798 (Growth factors & signalling).